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3.
tional age 24 weeks and 42 weeks, and records with 151 charts of infants who were 34 weeks’ gestational
missing data. Of the total births in Massachusetts, 67 884 age and admitted to the NICU in a rural Illinois hospital
(84%) met inclusion criteria for this study. Breastfeeding and found a breastfeeding initiation rate of 49.7%, with
initiation rates were lowest among preterm infants of no signiﬁcant association with maternal race/ethnicity.19
the youngest gestational ages. Breastfeeding initiation A study by Geraghty et al20 examined breastfeeding rates
was 76.8% among term infants born at 37 to 42 weeks, among term and preterm infants, but the research was
70.1% among infants born at 32 to 36 weeks, and 62.9% restricted to multiple births. In addition, although the
among infants born at 24 to 31 weeks. In univariate Centers for Disease Control and Prevention (CDC) Preg-
analysis, among preterm infants, a lower proportion of nancy Risk Assessment Monitoring System collects both
US-born black, Asian, and Hispanic mothers initiated breastfeeding rates information22,23 and data on gesta-
breastfeeding than US-born white mothers; non–US- tional age,24 we have not been able to identify any Preg-
born black and non–US-born Hispanic mothers had the nancy Risk Assessment Monitoring System– based stud-
highest breastfeeding initiation rates. Among term in- ies that examined both together.
fants, US-born black mothers had the lowest initiation National surveys calculate breastfeeding rates among
rates, and non–US-born black and non–US-born His- term infants according to maternal race/ethnicity, but
panic mothers had the highest. In multivariate logistic maternal birthplace is not recorded. Maternal birthplace
regression, however, after controlling for mother’s age, likely is important because breastfeeding is the cultural
race, birthplace, and insurance, US-born white mothers norm in the countries of origin for many non–US-born
were least likely to breastfeed either term or preterm US residents. The goals of this study were to compare
infants when compared with any other racial/ethnic breastfeeding initiation rates among preterm and term
group, including US-born black mothers. The likelihood infants in Massachusetts in 2002 and to investigate the
that non–US-born Hispanic mothers would breastfeed role of maternal birthplace and race/ethnicity on breast-
was almost 8 times greater than that for US-born white feeding initiation.
mothers for a preterm infant and almost 10 times greater
for a term infant. In multivariate logistic regression anal-
ysis stratiﬁed by gestational age for both preterm and METHODS
term infants, older mothers and mothers with private Massachusetts Community Health Information Proﬁle
health insurance were most likely to breastfeed. (MassCHIP)25 is a public health database that was created
by the Massachusetts Department of Public Health and
CONCLUSIONS. In Massachusetts, preterm infants were less provides online public access to 32 data sets on health
likely to receive breast milk than term infants, and the outcomes, program utilization, and demographic indica-
likelihood of receiving breast milk was lowest among the tors at the local community and statewide levels. We
youngest preterm infants. In multivariate logistic regres- created a custom report using the Massachusetts natality
sion, mothers who were born outside the United States (vital records) database, accessed through MassCHIP, for
were more likely than US-born mothers to breastfeed 2002, the most recent year available in 2005 when the
either term or preterm infants in all racial and ethnic study began. Breastfeeding data in Massachusetts are
groups. In an unexpected ﬁnding, US-born white moth- obtained from the mother by the birthing hospital dur-
ers were less likely to breastfeed term or preterm infants ing the postpartum stay and entered into the electronic
than US-born black mothers or mothers of any other birth certiﬁcate. Each hospital is responsible for creating
racial or ethnic group. a protocol for obtaining these data. The birth certiﬁcate
question is, “Are you breastfeeding, or do you intend to
breastfeed? Yes or no.” The Massachusetts Department
B REASTFEEDING IS THE optimal form of infant nutri-
tion.1 Among premature infants, formula feeding
increases the risk for necrotizing enterocolitis,2 delayed
of Public Health subsequently enters the birth certiﬁcate
data into the MassCHIP database (masschip.state.ma.us).
Birth-linked demographics and data also accessed
brainstem maturation,3 decreased scoring on cognitive through MassCHIP were maternal age (categorized as
and developmental tests,4–7 sepsis,8 and delayed visual 15–19, 20 –29, or 30 –39 years), race/ethnicity (catego-
development.9,10 With this in mind, many interventions rized as white/non-Hispanic, black/non-Hispanic, His-
are designed to increase breast milk consumption among panic, or Asian/Paciﬁc Islander/non-Hispanic), maternal
preterm infants.11–16 However, breastfeeding rates among birthplace (categorized as US-born [50 states; Washing-
US preterm infants are not available; the national sur- ton, DC; and Puerto Rico] or non–US-born), health in-
veys17,18 that report annual breastfeeding rates do not surance (public or private) as an indicator of socioeco-
report gestational age. Although data are collected in nomic status, and infant’s gestational age (GA;
states where gestational age and breastfeeding are re- categorized as 24 –31, 32–36, or 37– 42 weeks). Race/
corded on the birth certiﬁcate, published work is re- ethnicity and birthplace were recoded into a single vari-
stricted to a few small studies.19–21 One study reviewed able for analysis. For creation of a data set with broad
PEDIATRICS Volume 118, Number 4, October 2006 e1049
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4.
applicability, certain exclusions were made. We ex- borns had a gestational age 37 weeks, and the overall
cluded mothers who were younger than 15 years (73) breastfeeding initiation rate for Massachusetts in 2002
and older than 39 years (3085), nonsingleton births was 74.6%. Among the 67 884 births that met inclusion
(3951), births to Native Americans (167), and infants for this analysis, the initiation rate was 76.4%. Preterm
with a GA 24 weeks (182) and 42 weeks (21). Native infants with the youngest gestational ages breastfed the
Americans were excluded because the number was too least: breastfeeding initiation was 76.8% among term
small to analyze, and infants at extreme ends of the infants ( 37– 42 weeks), 70.1% among infants who
gestational age range were excluded because of potential were born at 32 to 36 weeks, and 62.9% among infants
medical complications that might affect breastfeeding. who were born at 24 to 31 weeks. Demographic infor-
We used health insurance as a marker for socioeconomic mation and breastfeeding initiation rates by gestational
status; therefore, we excluded insurance types that did age are presented in Table 1.
not clarify income (non-Medicaid/Medicare government Among preterm infants, a lower proportion of US-
insurance [2090] and self-pay [471]). An additional born blacks, Asian, and Hispanic mothers initiated
4064 records were excluded because 1 of the following breastfeeding than US-born white mothers, whereas
variables was missing: maternal age (176), insurance
non–US-born black and non–US-born Hispanic mothers
status (1918), race (1530), or birthplace (93) or infant’s
had the highest breastfeeding initiation rates (Table 2).
GA (347). A total of 12 740 births (fewer than the sum
Among term infants, US-born black mothers had the
of the individual categories, because some exclusions fell
lowest initiation, followed closely by US-born white and
into 1 category) were excluded, leaving 67 884 births
Hispanic mothers. Again, non–US-born black and non–
for analysis.
US-born Hispanic mothers had the highest initiation
Descriptive analysis included frequencies. We ﬁrst as-
rates for term infants. For both preterm and term in-
sessed breastfeeding initiation rates for preterm (24 –36
weeks’ GA) and term infants, overall, and stratiﬁed by fants, breastfeeding initiation increased with increasing
maternal factors (age, race/ethnicity/birthplace, and in- maternal age and private insurance status.
surance). We then assessed the association between GA In multivariate analysis (Table 3), controlling for
(preterm 24 –31 weeks, preterm 32–36 weeks, and mother’s age, insurance, race, and birthplace, infants
term), ﬁrst on a univariate basis and then adjusted for all who were born between 32 and 36 weeks had an ad-
other variables in the model. Finally, we used univariate justed odds ratio (AOR) of 0.73 (95% conﬁdence inter-
and multivariate logistic regression to assess the role of val [CI]: 0.68 – 0.79) for breastfeeding compared with
maternal factors in predicting breastfeeding initiation. term infants, and infants who were born between 24
Data were analyzed using Stata/SE 8.2 for Windows and 31 weeks had an AOR of 0.53 (95% CI: 0.44 – 0.64).
(Stata Corp, College Station, TX). Although US-born black mothers were least likely to
initiate breastfeeding in descriptive analysis and univar-
RESULTS iate logistic regression, once maternal age, insurance
On the basis of MassCHIP data for 2002, there were status, and gestational age were controlled for, US-born
80 624 births in Massachusetts; 8.2% (6611) of new- black mothers were statistically signiﬁcantly more likely
TABLE 1 Population Sample Breastfeeding and Maternal Factors Stratiﬁed According to GA
Young Preterm Older Preterm Term
(24–31 wk; (32–36 wk; (37–42 wk;
N 534), n (%) N 3367), n (%) N 63 983), n (%)
Breastfeeding initiated 336 (62.9) 2361 (70.1) 49 149 (76.8)
Maternal age, y
15–19 68 (12.7) 300 (8.9) 3603 (5.6)
20–29 204 (38.2) 1308 (38.9) 25 050 (39.2)
30–39 262 (49.1) 1759 (52.2) 35 330 (55.2)
Insurance status
Private 324 (60.7) 2240 (66.5) 46 665 (72.9)
Public 210 (39.3) 1127 (33.5) 17 318 (27.1)
Maternal race/ethnicity and birthplace
White, US born 285 (53.4) 2092(62.1) 42 480 (66.4)
White, non–US born 23 (4.3) 190 (5.6) 4936 (7.7)
Asian, US born 3 (0.6) 37 (1.1) 438 (0.7)
Asian, non–US born 36 (6.7) 204 (6.1) 4112 (6.4)
Black, US born 69 (13) 225 (6.7) 2410 (3.8)
Black, non–US born 30 (5.6) 151 (4.5) 2077 (3.3)
Hispanic, US born 58 (11) 286 (8.0) 3905 (6.1)
Hispanic, non–US born 30 (5.6) 200 (5.9) 3625 (5.7)
e1050 MEREWOOD et al
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6.
TABLE 4 Results of Logistic Regression: Factors That Are Associated With Breastfeeding Initiation, Stratiﬁed According to GA
Preterm Infants (Born 24–36 wk; N 3901) Term Infants (Born 37–42 wk; N 63 983)
Unadjusted OR (95% CI) AOR (95% CI) Unadjusted OR (95% CI) AOR (95% CI)
Maternal age, y
15–19 Reference Reference Reference Reference
20–29 1.71 (1.36–2.16) 1.50 (1.17–1.92) 1.52 (1.41–1.64) 1.14 (1.05–1.24)
30–39 2.42 (1.93–3.04) 1.70 (1.31–2.20) 2.31 (2.15–2.49) 1.53 (1.41–1.66)
Insurance status
Private Reference Reference Reference Reference
Public 0.42 (0.37–0.49) 0.35 (0.29–0.41) 0.53 (0.51–0.55) 0.41 (0.39–0.43)
Maternal race/ethnicity and birthplace
White, US born Reference Reference Reference Reference
White, non–US born 1.85 (1.32–2.61) 2.40 (1.69–3.42) 2.73 (2.50–2.99) 3.39 (3.10–3.72)
Asian, US born 0.92 (0.48–1.78) 1.28 (0.64–2.56) 1.41 (1.12–1.78) 1.75 (1.38–2.23)
Asian, non–US born 1.60 (1.17–2.17) 1.85 (1.35–2.55) 1.59 (1.46–1.72) 1.79 (1.65–1.94)
Black, US born 0.71 (0.55–0.91) 1.27 (0.97–1.66) 0.85 (0.78–0.93) 1.44 (1.31–1.59)
Black, non–US born 2.07 (1.42–3.03) 3.10 (2.09–4.61) 3.74 (3.21–4.36) 5.81 (4.97–6.80)
Hispanic, US born 0.86 (0.68–1.10) 1.73 (1.32–2.26) 0.97 (0.90–1.04) 1.84 (1.70–1.99)
Hispanic, non–US born 4.26 (2.77–6.56) 7.61 (4.88–11.9) 5.35 (4.67–6.13) 9.60 (8.35–11.0)
Unadjusted OR is the OR from univariate logistic regression; AOR is the OR from multivariate logistic regression. The multivariate model controls for all variables presented (maternal age, insurance
status, race/ethnicity, and birthplace).
For example, non–US-born black mothers were 3.1 certain non–US-born groups (Table 3), we examined the
times more likely to initiate breastfeeding in their pre- makeup of non–US-born Massachusetts residents. Ac-
term infants than US-born white mothers, and non–US- cording to the 2000 US census, 772 983 (12%) Massa-
born Hispanic mothers were 7.6 times more likely. chusetts residents were born outside the United States.
Breastfeeding rates among black mothers of preterm Within this group, the largest proportions were from
infants are particularly noteworthy because black infants Europe (32.2%), Latin America (30.0%; comprising Ca-
are almost twice as likely to be born preterm as white ribbean [14.5%], South America [9.3%], and Central
infants27 (a trend that was apparent in our study [Table America [6.5%]), and Asia (26.1%).25
1]). In addition to our ﬁndings on non–US-born black One possible limitation of the study is whether exclu-
mothers and infants, we note that, among both preterm sions led to outcomes that were not representative of the
and term infants, US-born black mothers had the lowest entire state. Exclusions were made to limit outlying cases
breastfeeding initiation rates, but after controlling for that might affect breastfeeding initiation, such as ex-
maternal factors and gestational age, US-born black tremely preterm infants with high mortality ( 24
mothers had higher breastfeeding initiation rates than weeks). We also excluded multiple births, which are
US-born white mothers. Black mothers are reported common in preterm deliveries, but with the limited data
consistently at the national level as having the lowest available, any reasons for variation in breastfeeding rates
breastfeeding rates.18,28 However, these data do not con- within this group would be difﬁcult to control for. It also
sider birthplace and are not adjusted for confounding. is a limitation of this study that we do not have infor-
Our results regarding maternal birthplace expand on mation on factors that are known to affect breastfeeding
those published in a recent, smaller study, which ana- initiation, such as substance abuse or maternal illness.
lyzed data on 4207 mothers and found that, looking at These variables may be responsible in part for the low
all ethnicities combined, US-born mothers had an 85% rates among preterm infants, rather than prematurity
reduction in the odds of initiating breastfeeding (OR: alone.
0.150; P .01) and a 66% reduction in the odds of The main limitation of the study, however, lies on our
breastfeeding at 6 months (OR: 0.344; P .01) when reliance on breastfeeding rate data from the electronic
compared with non–US-born mothers. That study also birth certiﬁcate. In this regard, we are reassured by the
found that each additional year of living in the United knowledge that the 2002 breastfeeding initiation rate
States was associated with a 4% decrease in the odds of obtained from the Massachusetts birth certiﬁcate
initiating breastfeeding (OR: 0.96; P .01) and a 3% (75%)28 is comparable to the 2002 initiation rate for
decrease in the odds of breastfeeding at 6 months (OR: Massachusetts described by the 2 prime sources of
0.97; P .05). Given these ﬁndings, we suggest that breastfeeding rate data nationally: the Ross Mothers’
national surveys, which currently report breastfeeding Survey (73%)18 and the CDC National Immunization
rates only on the basis of race, need consistently to Survey (74%),28 which use different data collection
consider maternal place of birth. methods. Generally, birth certiﬁcate data are widely
Because rates of breastfeeding are so relatively high in used in research, and published studies that have used
e1052 MEREWOOD et al
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9.
Maternal Birthplace and Breastfeeding Initiation Among Term and Preterm
Infants: A Statewide Assessment for Massachusetts
Anne Merewood, Daniel Brooks, Howard Bauchner, Lindsay MacAuley and Supriya
D. Mehta
Pediatrics 2006;118;e1048-e1054
DOI: 10.1542/peds.2005-2637
Updated Information including high-resolution figures, can be found at:
& Services http://www.pediatrics.org/cgi/content/full/118/4/e1048
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